In the ongoing fight against Islamic State, the US is said to be attacking militants with “cyber bombs” according to Deputy Defense Secretary Robert Work.

Reuters reports that Work explained the approach during an interview earlier this week, though he didn’t explain what those bombs involved or exactly how they were targeted. But he did add that “those guys are under enormous pressure... Every time we have gone after one of their defended positions over the last six months, we have defeated them. They have left, they have retreated.”

The digital attacks have been in the works for a while now. Secretary of Defense Ash Carter has in the past explained that the plan for the cyber onslaught against Islamic State was “to cause them to lose confidence in their networks, to overload their network so that they can’t function, and do all of these things that will interrupt their ability to command and control forces there, control the population and the economy.”